Enzyme inhibitors are important class of molecules that are used as drugs and pesticides. The enzyme acetylcholinesterase (AchE) is involved in the synaptic transmission of the nerve impulse and its inhibition leads to accumulation of the neurotransmitter, acetylcholine leading to overexcitation of the postsynaptic neuron. This property of the inhibitor has been exploited to develop newer insecticides against a wide range of insect pests as well as drugs effective against worms, and, recently a new class of neuroactive drugs against dementia (Alzheimer's).
Although earlier authors have isolated metabolites such asasteric acis, questin and questinol from Sorortricum sp., no AchE inhibitor activity has been reported(Slater, G P, Haskins, R H and Hogge, L. R. Can J Mirobiol 17 (1971), 1576–79). The fungi, Aspergillus terreus ( Ling, K H, Liou, H H, Yang, C M and Yang C K, Appl. Env. Microbiol, 37 (1979) 355–57) and Penicillium sp. (Omura, Skuno, F, Otoguro, K, Shiomi, K. Mauma, R and Iwai, Y. J. Antibiot. 48(1995) 745–46) have been reported to produce an AchE inhibitor named Arusigacin. However, the AchE inhibitor of the present invention is isolated from Sporotrichum having distinct chemical structure and properties and therefore a novel inhibitor molecule.
After screening of various microorganisms, a fungal culture is selected which shows inhibition against a serine esterase/protease/cholinesterase enzyme. This imperfect deuteromycetes, Sporotrichum species and was first isolated in 1966. The taxonomic features of Sporotrichum species (deuteromyces) are broad hyphae and septate in nature; has hyalline conidiophores with little differentiation from vegetatative hyphae and solitary conidia with broad attachment to the hyphae.
This culture has previously been a subject of research investigation at the Central Food Technological Research Institute (CFTRI) India, for its ability to grow on lignocellulosic wastes for the production of enzymes and organic acids (Sreekantaiah, K R, PhD thesis (1976) University of Mysore; Manonmani, H K, PhD thesis (1986) University of Mysore).
This culture has now been used in the present invention to produce a fermented extract containing a serine esterase/protease/cholinesterase inhibitor.
The conditions of fermentation have been described earlier in Indian Patent Application No. 303/DEL/2000 Sattur, A P, Shivanandappa, T, Divakar, S and Karanth, N G.